Browsing by Author "Singh, Bhagat"

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Dissecting chickpea genomic loci associated with the root penetration responsive traits in compacted soil
(Springer Nature Publishing AG, 2024) Donde, Ravindra; Kohli, Pawandeep Singh; Pandey, Mandavi; Sirohi, Ujjwal; Singh, Bhagat; Giri, Jitender
Soil compaction is a major concern for modern agriculture, as it constrains plant root growth, leading to reduced resource acquisition. Phenotypic variation for root system architecture (RSA) traits in compacted soils is present for various crops; however, studies on genetic associations with these traits are lacking. Therefore, we investigated RSA traits in diferent soil compaction levels and identifed signifcant genomic associations in chickpea. We conducted a Genome-Wide Association Study (GWAS) of 210 chickpea accessions for 13 RSA traits under three bulk densities (BD) (1.1BD, 1.6BD, and 1.8BD). Soil compaction decreases root exploration by reducing 12 RSA traits, except average diameter (AD). Further, AD is negatively correlated with lateral root traits, and this correlation increases in 1.8BD, suggesting the negative efect of AD on lateral root traits. Interestingly, we identifed probable candidate genes such as GLP3 and LRX for lateral root traits and CRF1-like for total length (TL) in 1.6BD soil. In heavy soil compaction, DGK2 is associated with lateral root traits. Reduction in laterals during soil compaction is mainly due to delayed seedling establishment, thus making lateral root number a critical trait. Interestingly, we also found a higher contribution of the GxE component of the number of root tips (Tips) to the total variation than the other lateral traits. We also identifed a pectin esterase, PPE8B, associated with Tips in high soil compaction and a signifcantly associated SNP with the relative change in Tips depicting a trade-of between Tips and AD. Identifed genes and loci would help develop soil-compaction-resistant chickpea varieties.
Editing cis-elements of OsPHO1;2 improved phosphate transport and yield in rice
(John Wiley & Sons, 2025) Maurya, Kanika; Mani, Balaji; Singh, Bhagat; Sirohi, Ujjwal; Jaskolowski, Aime; Sharma, Sandeep; Tatiparthi, Harsha Vardhan; Mangrauthia, Satendra Kumar; Pandey, Renu; Poirier, Yves; Giri, Jitender
Increasing grain yield is the primary goal of crop improvement, which is globally affected by the low availability of soil phosphate (Pi). Overexpressing Pi transporters to enhance Pi uptake often results in Pi toxicity and growth retardation. Despite advances in genetic engineering, targeting the cis-regulatory motifs of Pi transporters remains underexplored for understanding plant mechanisms and improving Pi status. Here, we demonstrate that the excision of the transcription inhibitor motif from the promoter of the Pi transporter OsPHO1;2 enhances its expression and increases root-to-shoot Pi transport, leading to improved grain yield. Through in silico and DNA-protein interaction studies, we show the role of the OsWRKY6 transcription factor in negatively regulating OsPHO1;2 expression by binding to the cis-regulatory element (W-box) present in its promoter. The oswrky6 knockout lines exhibit higher OsPHO1;2 expression and improved shoot Pi levels. Furthermore, we engineered the OsPHO1;2 promoter to precisely remove the W-box and enhance OsPHO1;2 expression. Phenotypic and physiological evaluations at the vegetative stage indicate that OsPHO1;2 promoter-edited (OsPHO1;2:PE) lines have increased shoot length, plant biomass and greater root-to-shoot Pi export under both low and normal P conditions. Notably, the 33P uptake assay reveals that OsPHO1;2:PE lines display enhanced root Pi uptake, supported by higher expression of root-associated Pi transporters (OsPHTs). An extensive agronomic assessment shows that OsPHO1;2:PE lines achieve increased seed and panicle numbers, thereby raising yield without affecting seed quality. Our findings provide valuable insights into the potential of promoter editing to improve Pi use and enhance crop yield.
A lipid synthase maintains metabolic flux for jasmonate synthesis to regulate root growth and phosphate homeostasis
(Oxford University Press, 2025) Pandey, Mandavi; Verma, Lokesh; Kohli, Pawandeep Singh; Singh, Bhagat; Kochi, Abhijith; Giri, Jitender
Plants require phosphate (Pi) for proper growth and development but often face scarcity of this vital nutrient in the soil. Pi-starvation triggers membrane lipid remodeling to utilize the membrane phospholipid-bound Pi in plants. In this process, phospholipids are replaced by non-Pi-containing galactolipids (MGDG, DGDG) and sulfolipids. The galactolipids ratio (MGDG:DGDG) is suggested to influence jasmonic acid (JA) biosynthesis. However, how the MGDG:DGDG ratio, JA levels, and root growth are coordinated under Pi deficiency in rice (Oryza sativa) remains unknown. Here, we characterized DGDG synthase 1 (OsDGD1) for its role in regulating root development by maintaining metabolic flux for JA biosynthesis. We showed that OsDGD1 is responsive under low Pi and is under the direct control of Phosphate Starvation Response 2 (OsPHR2), the master regulator of low Pi adaptations. Further, OsDGD1 knockout (KO) lines showed marked phenotypic differences compared to the wild type (WT), including a significant reduction in root length and biomass, leading to reduced Pi uptake. Further, lipidome analyses revealed reduced DGDG levels in the KO line, leading to reduced membrane remodeling, thus affecting P utilization efficiency. We also observed an increase in the MGDG: DGDG ratio in KO lines, which enhanced the endogenous JA levels and signaling. This imbalance of JA in KO plants led to changes in auxin levels, causing drastic root growth inhibition. These findings indicate the critical role of OsDGD1 in maintaining optimum levels of JA during Pi deficiency for conducive root growth. Besides acting as signaling molecules and structural components, our study widens the role of lipids as metabolic flux controllers for phytohormone biosynthesis.
Phosphate deficiency inducible OsGDPD5 affects root growth by regulating sugar-auxin crosstalk
(John Wiley & Sons, 2025) Verma, Lokesh; Pandey, Mandavi; Bhatia, Chitra; Mehra, Poonam; Singh, Bhagat; Giri, Jitender
Glycerophosphodiester phosphodiesterases (GDPDs) enzymes are known to be involved in phospholipids degradation pathways, where glycerophosphodiesters are hydrolyzed to glycerol-3-phosphate (G3P) and corresponding alcohol. In plants, GDPDs are involved in phosphate deficiency adaptive responses and have been shown to impact root length, but the precise mechanism remains unclear. This study focuses on the rice GDPD5 gene and its role in regulating primary root growth. Our research demonstrates that OsGDPD5 encodes a functional GDPD enzyme and could hydrolyze glycerophosphocholine and glycerophosphorylethanolamine. At transcriptional levels, OsGDPD5 is preferentially expressed in the root tip and regulated by transcription factor OsPHR2. We have used CRISPR/Cas9 to generate OsGDPD5 knock-out lines, allowing us to explore its role in root growth. Our findings show that osgdpd5 mutants had a shorter primary root, which could be restored to a normal level by the exogenous application of sugar or G3P. Further, knocking out OsGDPD5 alters endogenous levels of G3P and sugars, affecting auxin biosynthesis in the root and, ultimately, primary root growth. In this manner, OsGDPD5 has a crucial role in regulating physiological processes, specifically sugar and auxin signaling, which are known to be involved in root growth regulation in rice. Our research thus unraveled a link between rice phosphate deficiency-responsive lipid remodeling and root growth via sugar-hormone signaling.
Physiological and genetic basis of superior phosphate uptake and utilization efficiency in the rice landrace Wazuhophek
(Oxford University Press, 2025) Kohli, Pawandeep Singh; Donde, Ravindra; Sirohi, Ujjwal; Singh, Bhagat; Anantha, M S; Bhadana, Vijai Pal; Sundaram, Raman Meenakshi; Mangrauthia, Satendra K; Giri, Jitender
Low phosphorus (P) availability due to edaphic conditions or the scarcity of P fertilizers restricts agricultural productivity. Various rice-growing regions experience poor P availability. Landraces from these regions, such as Wazuhophek in Northeast India, may provide a source of critical genetic variation needed for developing highly efficient, tolerant rice varieties. This study identifies the physiological and genetic basis of higher efficiency and tolerance in Wazuhophek. Wazuhophek displays higher shoot P content across three different P regimes (0, 15, and 200 µM P) compared to the sensitive parent, Improved Samba Mahsuri (ISM). In 0 µM, Wazuhophek’s increased shoot P content can be attributed to greater root physiological P use efficiency and improved root-to-shoot P translocation. At 15 and 200 µM P, Wazuhophek exhibited a higher crown root number and surface area, with more efficient roots than ISM, facilitating better Pi acquisition and higher shoot P. Furthermore, the genetic basis was delineated by identifying quantitative trait loci (QTLs) for critical traits. Revealing Wazuhophek’s physiological mechanism of low P tolerance provides valuable insights for developing rice varieties suited for nutrient-poor soil. Additionally, the identified QTLs for key traits offer targets for breeding more efficient low P-tolerant rice.